1. Technical Field
The present invention relates to an image forming apparatus.
2. Related Art
Due to environmental considerations, EA (emulsion aggregation) toners using a wet production method are being used as toners in recent image forming apparatuses, enabling a reduction in the fixing temperature thereof. In order to achieve an even greater reduction in the fixing temperature crystalline binder polymers are gradually being introduced.
It is known that EA toners have poor cleaning characteristics in comparison to pulverized toners, and that crystalline binder polymers have poor charging characteristics. Consequently, there is a tendency to include a greater proportion of external additives in EA toners, in comparison to pulverized toners, in order to adjust the level of charge and maintain adequate cleaning.
Among such additives, in particular external additives of about 100 nm that are comparatively shaped with angular portions removed therefrom are used as transfer agents, in order to improve developability. However, such external additives readily pass beneath cleaning blades, though toner particles do not pass beneath the cleaning blade, so there is a tendency for external additive filming to occur. Therefore, recent toners are in a state susceptible to problems due to external additive filming due to becoming external-additive-rich.
A particular example of a problem caused by external additive filming is ghost images (ghosting). Within categories of ghosting there is known ghosting caused by localized changes in sensitivity and known ghosting caused by latent image electrical potential due to changes in Rp (residual potential), and also known ghosting caused by the surface condition of a photoreceptor.